508 safford: lignum nephriticum 



fact that all specimens seen by the writer were either shrubs or 

 trees too small to yield wood for the manufacture of bowls and 

 cups, the writer was inclined to agree with Moller in discarding 

 Eysenhardtia as a source of the famous wood. In July, 1914, 

 however, specimens of a medicinal wood from Mexico were 

 brought to the writer accompanied by herbarium material from 

 the same tree sufficient to identify it. It proved to be Eysen- 

 hardtia polystachya, commonly known by the modern Mexicans 

 in many localities as palo dulce, or ''sweet wood." Its collector 

 had not noticed anything peculiar about the color of its infusion, 

 but dwelt upon its efficacy as a cure for certain diseases to which 

 fowls are subject in Mexico. The wood was a section of a tree 

 trunk, whicli deprived of its bark was 7 cm. in diameter, and 

 which, unhke all specimens of Ej^senhardtia wood hitherto 

 seen by the writer, consisted chiefly of dark brown, dense, fine- 

 grained heartwood very much like Guaiacum officinale in appear- 

 ance, surrounded by a ring of brownish-white sapwood 5 to 8 mm. 

 thick. A few small chips of the heartwood in ordinary tap- 

 water tinged the latter a golden yellow, which soon deepened to 

 orange, and looked like amber when held between the eye and the 

 window. When the glass vial containing the liquid was held 

 against a dark background the liquid glowed with a beautiful 

 peacock blue fluorescence, very much like that seen in quinine. 

 Placed partly in a sunbeam, half of the hquid appeared yellow and 

 the other half blue; and when the sunlight was focused upon it 

 by the lens of a common reading glass, the vial appeared to be 

 filled with radiant gold penetrated by a shaft of pure cobalt. 

 There was no longer any doubt as to the identity of the wood. 

 It could only be the true lignum nephriticum of Robert Boyle's 

 experiments; and it was undoubtedly the wood of Eysenhardtia 

 polystachya, a tree with small pinnately compound leavs which 

 might well suggest those of a chick-pea or of the common wild 

 rue of Spain, and with spikes of small flowers which had turned 

 yellowish in drying, corresponding with Hernandez's description 

 of the coatl of the Aztecs. 



Chips of the sapwood tinged tap-water only slightly at first, 

 but when left over-night the infusion deepened to a greenish 



